In the use of an auger in conveying fine bulk materials, it has been found that such usage results in an unsteady and uneven flow of materials, and even stoppage due to clogging. Such effects have been found to be caused by the accumulation and settlement of fine material particles in the spacing between helical flights which diminishes and possibly blocks the flow of material through the conveyance device. The result of such accumulation and settlement of material particles is a loss of capacity due to material accumulation diminishing the space between helical flights, and a reduction in the uniformity of the material being conveyed due to the detachment and discharge of segments of material lodged in helical flights. The deeper the spacing between helical flights, the greater the accumulation and settlement of material sought to be conveyed.
U.S. Pat. No. 8,011,861 to Sprouse and U.S. Pat. No. 1,258,911 to Kinyon show conventional connections for feeding air to into the open end of a hollow shaft to discharge through radial holes of the hollow shaft.
The rotary connection of the air supply in the U.S. Pat. No. 8,011,861 to Sprouse, illustration reference number 156, is very similar in concept to commercially-available rotary unions. That is, it employs an internal bearing 168, an internal seal 176, a hollow shaft 134 & 170 and a stationary housing 162 not noticeably connected to the feeder and which is piped to a remote gas supply 160. The only distinctions are (1) the auger shaft 134 extends into and comprises a part of the rotary connection rather than being externally coupled to it and (2) the bearing within the rotary connection appears to act as a support point for auger shaft 134.
Kinyon (U.S. Pat. No. 1,258,911) describes the connection between the hollow auger shaft—illustration reference 7—and the air supply conduit—reference 12—as a “packed joint” reference 13. Based upon the vintage of the patent, the described function of the “packed joint” and its name, it is apparent its “packed joint” is an arrangement also known to engineers and mechanical tradesmen as a “stuffing box” or “packing gland”. This class of rotary seal consists of a generally stationary housing which a shaft passes through. In the Kinyon patent, the stationary housing of packed joint 13 is rigidly attached to stationary air conduit 12, which conduit ends near its attachment point to the packed joint. Rotating hollow shaft 7 is inserted into the stationary housing, through the follower and the packing material to end just short of contact with the end of air conduit 12. The “packed j oint” employed by Kinyon is an adaptation of the ubiquitous packing gland.
Accumulation of powdered material between helical flights reduces the cubic feet per revolution capacity of an auger shaft and thus requires operating the feed mechanism at higher rotational speeds to attain the same feed rate when there is no such blockage. Accordingly, it is the principal object of the present invention to provide an apparatus for receiving, conveying and discharging a fine bulk material, utilizing a helical shaft for impelling such material in a continuous and uniform flow pattern.